Spatial-temporal variables for swimming coaches: A comparison study between video and TritonWear sensor

Abstract

The main aim of this study was to evaluate the validity and the reliability of a swimming sensor to assess swimming performance and spatial-temporal variables. Six international male open-water swimmers completed a protocol which consisted of two training sets: a 6×100m individual medley and a continuous 800 m set in freestyle. Swimmers were equipped with a wearable sensor, the TritonWear to collect automatically spatial-temporal variables: speed, lap time, stroke count (SC), stroke length (SL), stroke rate (SR), and stroke index (SI). Video recordings were added as a “gold-standard” and used to assess the validity and the reliability of the TritonWear sensor. The results show that the sensor provides accurate results in comparison with video recording measurements. A very high accuracy was observed for lap time with a mean absolute percentage error (MAPE) under 5% for each stroke (2.2, 3.2, 3.4, 4.1% for butterfly, backstroke, breaststroke and freestyle respectively) but high error ranges indicate a dependence on swimming technique. Stroke count accuracy was higher for symmetric strokes than for alternate strokes (MAPE: 0, 2.4, 7.1 & 4.9% for butterfly, breaststroke, backstroke & freestyle respectively). The other variables (SL, SR & SI) derived from the SC and the lap time also show good accuracy in all strokes. The wearable sensor provides an accurate real time feedback of spatial-temporal variables in six international open-water swimmers during classical training sets (at low to moderate intensities), which could be a useful tool for coaches, allowing them to monitor training load with no effort.

Wearables in Swimming for Real-Time Feedback: A Systematic Review

“…Table 2 summarizes the aims of the studies, the participants´ demographics, and the swim strokes. From the 18 articles included for qualitative synthesis, eight (44.4%) [ 21 , 23 , 24 , 25 , 30 , 31 , 34 , 38 ] assessed wearables exclusively in front crawl, six (33.3%) [ 26 , 27 , 29 , 32 , 33 , 35 ] assessed wearables exclusively in all four swim strokes, two assessed wearables for the tumble turn in front crawl (11.1%) [ 36 , 37 ], one just assessed wearables in breaststroke (5.5%) [ 22 ], and another one assessed wearables in butterfly stroke (5.5%) [ 28 ]. Overall, 177 swimmers were recruited in all studies (103 males, 62 females, and 12 that the authors failed to note the sex of the participants).…”

“…Overall, 177 swimmers were recruited in all studies (103 males, 62 females, and 12 that the authors failed to note the sex of the participants). Four articles recruited elite-level swimmers (22.2%) [ 29 , 32 , 34 , 37 ], two articles recruited international-level participants (11.1%) [ 33 , 35 ], four articles recruited national-level/semi-professional participants (22.2%) [ 22 , 28 , 35 , 38 ], one article recruited local-level participants (5.5%) [ 31 ], and three articles recruited local/non-expert swimmers (16.7%) [ 22 , 25 , 36 ]. Conversely, six articles (33.3%) [ 21 , 23 , 24 , 26 , 27 , 30 ] did not report the swimmers’ competitive level.…”

“…Table 3 consolidates the details on the assessed sensor, the anatomical landmark where it was placed, variables analyzed, and the main findings of the studies. Fourteen studied accelerometers (77.8%) [ 21 , 22 , 23 , 24 , 25 , 26 , 27 , 29 , 32 , 33 , 35 , 36 , 37 , 38 ], seven studied microcontroller units (MCUs) (38.9%) [ 22 , 25 , 26 , 27 , 28 , 29 , 37 ], six studied IMUs (33.3%) [ 21 , 22 , 23 , 24 , 28 , 31 ], three studied visual feedback (16.7%) [ 25 , 26 , 27 ], and just one studied a gyroscope (5.5%) [ 34 ].…”

“…About the anatomical landmark, eight studies placed the wearable on the lower back (44.4%) [ 21 , 22 , 23 , 29 , 34 , 36 , 37 , 38 ], seven on the head (38.9%) [ 24 , 25 , 26 , 27 , 28 , 33 , 35 ], and five on the wrist (27.8%) [ 21 , 25 , 26 , 27 , 30 ] ( Table 3 ). Overall, the articles identified and/or measured variables related to kinematics and kinetics (e.g., duration of the stroke, stroke count, stroke rate, speed) during the arm stroke.…”

“…Figure 1 depicts the PRISMA flow diagram for identifying, screening, and checking eligibility, which then helps to determine inclusion of the articles. A total of 18 articles [ 21 , 22 , 23 , 24 , 25 , 26 , 27 , 28 , 29 , 30 , 31 , 32 , 33 , 34 , 35 , 36 , 37 , 38 ] were included in the qualitative synthesis.…”